/*
 * Copyright (c) 2007, 2021, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.sun.org.apache.xpath.internal.axes;

import com.sun.org.apache.xml.internal.dtm.DTM;
import com.sun.org.apache.xml.internal.dtm.DTMAxisIterator;
import com.sun.org.apache.xml.internal.dtm.DTMFilter;
import com.sun.org.apache.xml.internal.dtm.DTMIterator;
import com.sun.org.apache.xpath.internal.Expression;
import com.sun.org.apache.xpath.internal.XPathContext;
import com.sun.org.apache.xpath.internal.compiler.Compiler;
import com.sun.org.apache.xpath.internal.compiler.OpMap;

/**
 * This class implements a general iterator for
 * those LocationSteps with only one step, and perhaps a predicate.
 *
 * @xsl.usage advanced
 * @see com.sun.org.apache.xpath.internal.axes#LocPathIterator
 */
public class OneStepIterator extends ChildTestIterator {
    static final long serialVersionUID = 4623710779664998283L;
    /**
     * The traversal axis from where the nodes will be filtered.
     */
    protected int m_axis = -1;

    /**
     * The DTM inner traversal class, that corresponds to the super axis.
     */
    protected DTMAxisIterator m_iterator;

    /**
     * Create a OneStepIterator object.
     *
     * @param compiler A reference to the Compiler that contains the op map.
     * @param opPos    The position within the op map, which contains the
     *                 location path expression for this itterator.
     * @throws javax.xml.transform.TransformerException
     */
    OneStepIterator(Compiler compiler, int opPos, int analysis)
            throws javax.xml.transform.TransformerException {
        super(compiler, opPos, analysis);
        int firstStepPos = OpMap.getFirstChildPos(opPos);

        m_axis = WalkerFactory.getAxisFromStep(compiler, firstStepPos);

    }


    /**
     * Create a OneStepIterator object.
     *
     * @param iterator The DTM iterator which this iterator will use.
     * @param axis     One of Axis.Child, etc., or -1 if the axis is unknown.
     * @throws javax.xml.transform.TransformerException
     */
    public OneStepIterator(DTMAxisIterator iterator, int axis)
            throws javax.xml.transform.TransformerException {
        super(null);

        m_iterator = iterator;
        m_axis = axis;
        int whatToShow = DTMFilter.SHOW_ALL;
        initNodeTest(whatToShow);
    }

    /**
     * Initialize the context values for this expression
     * after it is cloned.
     *
     * @param context The XPath runtime context for this
     *                transformation.
     */
    public void setRoot(int context, Object environment) {
        super.setRoot(context, environment);
        if (m_axis > -1)
            m_iterator = m_cdtm.getAxisIterator(m_axis);
        m_iterator.setStartNode(m_context);
    }

    /**
     * Detaches the iterator from the set which it iterated over, releasing
     * any computational resources and placing the iterator in the INVALID
     * state. After<code>detach</code> has been invoked, calls to
     * <code>nextNode</code> or<code>previousNode</code> will raise the
     * exception INVALID_STATE_ERR.
     */
    public void detach() {
        if (m_allowDetach) {
            if (m_axis > -1)
                m_iterator = null;

            // Always call the superclass detach last!
            super.detach();
        }
    }

    /**
     * Get the next node via getFirstAttribute && getNextAttribute.
     */
    protected int getNextNode() {
        return m_lastFetched = m_iterator.next();
    }

    /**
     * Get a cloned iterator.
     *
     * @return A new iterator that can be used without mutating this one.
     * @throws CloneNotSupportedException
     */
    public Object clone() throws CloneNotSupportedException {
        // Do not access the location path itterator during this operation!

        OneStepIterator clone = (OneStepIterator) super.clone();

        if (m_iterator != null) {
            clone.m_iterator = m_iterator.cloneIterator();
        }
        return clone;
    }

    /**
     * Get a cloned Iterator that is reset to the beginning
     * of the query.
     *
     * @return A cloned NodeIterator set of the start of the query.
     * @throws CloneNotSupportedException
     */
    public DTMIterator cloneWithReset() throws CloneNotSupportedException {

        OneStepIterator clone = (OneStepIterator) super.cloneWithReset();
        clone.m_iterator = m_iterator;

        return clone;
    }


    /**
     * Tells if this is a reverse axes.  Overrides AxesWalker#isReverseAxes.
     *
     * @return true for this class.
     */
    public boolean isReverseAxes() {
        return m_iterator.isReverse();
    }

    /**
     * Get the current sub-context position.  In order to do the
     * reverse axes count, for the moment this re-searches the axes
     * up to the predicate.  An optimization on this is to cache
     * the nodes searched, but, for the moment, this case is probably
     * rare enough that the added complexity isn't worth it.
     *
     * @param predicateIndex The predicate index of the proximity position.
     * @return The pridicate index, or -1.
     */
    protected int getProximityPosition(int predicateIndex) {
        if (!isReverseAxes())
            return super.getProximityPosition(predicateIndex);

        // A negative predicate index seems to occur with
        // (preceding-sibling::*|following-sibling::*)/ancestor::*[position()]/*[position()]
        // -sb
        if (predicateIndex < 0)
            return -1;

        if (m_proximityPositions[predicateIndex] <= 0) {
            XPathContext xctxt = getXPathContext();
            try {
                OneStepIterator clone = (OneStepIterator) this.clone();

                int root = getRoot();
                xctxt.pushCurrentNode(root);
                clone.setRoot(root, xctxt);

                // clone.setPredicateCount(predicateIndex);
                clone.m_predCount = predicateIndex;

                // Count 'em all
                int count = 1;
                int next;

                while (DTM.NULL != (next = clone.nextNode())) {
                    count++;
                }

                m_proximityPositions[predicateIndex] += count;
            } catch (CloneNotSupportedException cnse) {

                // can't happen
            } finally {
                xctxt.popCurrentNode();
            }
        }

        return m_proximityPositions[predicateIndex];
    }

    /**
     * The number of nodes in the list. The range of valid child node indices
     * is 0 to <code>length-1</code> inclusive.
     *
     * @return The number of nodes in the list, always greater or equal to zero.
     */
    public int getLength() {
        if (!isReverseAxes())
            return super.getLength();

        // Tell if this is being called from within a predicate.
        boolean isPredicateTest = (this == m_execContext.getSubContextList());

        // And get how many total predicates are part of this step.
        int predCount = getPredicateCount();

        // If we have already calculated the length, and the current predicate
        // is the first predicate, then return the length.  We don't cache
        // the anything but the length of the list to the first predicate.
        if (-1 != m_length && isPredicateTest && m_predicateIndex < 1)
            return m_length;

        int count = 0;

        XPathContext xctxt = getXPathContext();
        try {
            OneStepIterator clone = (OneStepIterator) this.cloneWithReset();

            int root = getRoot();
            xctxt.pushCurrentNode(root);
            clone.setRoot(root, xctxt);

            clone.m_predCount = m_predicateIndex;

            int next;

            while (DTM.NULL != (next = clone.nextNode())) {
                count++;
            }
        } catch (CloneNotSupportedException cnse) {
            // can't happen
        } finally {
            xctxt.popCurrentNode();
        }
        if (isPredicateTest && m_predicateIndex < 1)
            m_length = count;

        return count;
    }

    /**
     * Count backwards one proximity position.
     *
     * @param i The predicate index.
     */
    protected void countProximityPosition(int i) {
        if (!isReverseAxes())
            super.countProximityPosition(i);
        else if (i < m_proximityPositions.length)
            m_proximityPositions[i]--;
    }

    /**
     * Reset the iterator.
     */
    public void reset() {

        super.reset();
        if (null != m_iterator)
            m_iterator.reset();
    }

    /**
     * Returns the axis being iterated, if it is known.
     *
     * @return Axis.CHILD, etc., or -1 if the axis is not known or is of multiple
     * types.
     */
    public int getAxis() {
        return m_axis;
    }

    /**
     * @see Expression#deepEquals(Expression)
     */
    public boolean deepEquals(Expression expr) {
        if (!super.deepEquals(expr))
            return false;

        if (m_axis != ((OneStepIterator) expr).m_axis)
            return false;

        return true;
    }


}
